Steam generators

ABSTRACT

A steam generator particularly for producing steam to be supplied to a flow of ventilation air for increasing the humidity thereof, comprising a water container, means for heating the water in the container in order to produce steam, means for supplying water to the container for replacing the water leaving the container as steam, means for intermittently draining off the water from the container so as to empty it for water with high mineral concentration in order to avoid or reduce permanent precipitations, the water inlet opening being spaced from the drain opening of the container and being located so as to cause agitation of the bottom water in the container when water is let thereinto. Preferably the valves are automatically operated in such a manner that the inlet valve is kept open when the draining valve is open whereby the bottom water with its precipitations is agitated during the draining operation.

United States Patent [151 3,682,141 Johansen [4 1 Aug. 8, 1972 [54]STEAM GENERATORS Primary Examiner-Kenneth W. S prague [72] Inventor:Birger Johan Walther Johansen, Amey Cra1g'Antnemand H111 Aarhus, Denmark7 ABSTRACT [73] Assignee: Birton Klima-og Koleteknlk A/S,

Mariedalsvej/truevej, Brabrand,

A steam generator particularly for producing steam to D enmark besupplied to a flow of ventilation air for increasing the humiditythereof, comprising a water container, [22] Filed: Sept. 2, 1970 meansfor heating the water in the container in order to produce steam, meansfor supplying water to the [211 App! 68844 container for replacing thewater leaving the container as steam, means for intermittently drainingoff the [52] US. Cl. ..l22/45l R, l22/382 water from the container so asto empty it for water [51] Int. Cl ..F22d 5/00 with high mineralconcentration in order to avoid or [58] Field of Search ..l22/382, 448R, 451 R, 448, reduce permanent precipitations, the water inlet open-122/451 ing being spaced from the drain opening of the container andbeing located so as to cause agitation of the [56] References Citedbottom water in the container when water is let thereinto. Preferablythe valves are automatically UNITED STATES PATENTS operated in such amanner that the inlet valve is kept 3 s 12 507 511970 Dixon 122/382 Openwhen the draining valve is p whereby the l:962:676 6/1934 Albright122/451 x \veter withits Preeipitetiens is agiteted during the 2,921,5641/1960 Mattox 122/382 drammg operauo" 3,377,994 4/1968 Home ..l22/382 7Claims 2 Drawing Figures T /0 /9/ :'i N

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INVENTOR.

BIRGER IOHAN WALTHER JOHANSEN BY Cvdm Hntonelti Shawna-1L P A TTORNE Y5STE GENERATORS The present invention relates to steam generators andmore specifically though not exclusively to electric steam boilers foruse in connection with air conditioning systems in order to supply steamto a flow of ventilation air and thus increase the humidity of the air.Still more specifically the invention relates to a steam generatorcomprising a water container having a stem outlet, a water inlet, andmeans for heating the water in the container in order to produce steam.

In such generators it is necessary to constantly or intermittentlysupply. water to the container in order to compensate for the waterleaving the container as steam, and it is known in the art to controlthe water supply in an automatic manner corresponding to the waterconsumption. An associated problem is that with the use of normalcalcarious water minerals and impurities will be left in the containerwhich, therefore, requires cleaning from time to time.

It is an object of the present invention to provide a steam generatorwhich may operate in a safe automatical manner with calcarious water.

A more specific object of the invention is to provide a steam generatorin which there is provided a special outlet opening for intermittentlydraining ofi the water from the container so as to generally avoid waterwith a too high concentration of minerals. During normal operation ofthe steam generator, when water is continuously or intermittently letinto the container for substituting the amount of water leaving thegenerator as steam, the mineral concentration in the water contents ofthe container will be steadily increasing because the mineral conetntsof the water does not leave the container together with the steam. Thus,after a while, heavy pricipitations may occur in the container and evenaffect the operation of the heating means, so it is desirable to emptythe container from time to time so as to let out all or almost all waterwith high mineral contents and let in new water of normal mineralcontents.

According to the invention the said inlet pipe is located so as todirect the inlet water generally towards the bottom portion of thecontainer, whilst the said outlet opening is located adjacent the bottomof the container preferably spaced from said inlet opening whereby thewater let into the container by normal operation will cause a certainagitation of the bottom water therein, so that precipitations are to atleast a considerable degree prevented from falling to rest on thecontainer bottom. When after a while the water is let out, preferablythrough a large diameter outlet pipe, the water will generally have amineral contents which is higher than in case of the inlet water beingintroduced without causing agitation in the bottom water, e.g., if thewater is let in vertically up through the bottom and thus generally awayfrom the bottom portion or bottom space of the container.

It is known in the art to provide automatical means for controlling theoperation of the inlet valve so as to maintain a generally constantwater level in the container, e.g., a water level varying between acertain minimum level and a certain maximum level. According to aspecial feature of the invention the said control means for the outletvalve are operatively connected additionally with said inlet valve so asto cause said inlet valve to be open during at least a period of thetime intervals in which the outlet valve is open. Especially withusually high pressure on the inlet water it will hereby be obtained thatthe bottom water is violently agitated during the draining off thereof,so that even heavier precipitation pieces already deposited on thecontainer bottom or elsewher will be mixed into the water so as to beable to leave the container together with the water.

In the following the invention is explained in more detail withreference to the accompanying drawing in which:

FIG. 1 is a schematical side view, partly in section, of an embodimentof a steam generator according to the invention, and

FIG. 2 is a top view of the water container thereof.

The steam generator shown comprises a closed water container 2 having alower water inlet pipe 4 in which there is mounted an electromagneticvalve 6. From the top cover of the container there projects a pair ofelectrode rods 8 down into the container, and an upper steam outlet pipe10 extends to a location in which the steam is to be used, e.g., forinjection into an air flow in a ventilation duct.

Also located adjacent the container bottom there is provided a thickoutlet pipe 12 connected to a drain pipe 14 through an electro magneticvalve 16. An overflow 18 from the container is connected to the drainpipe 14.

In the current feeding cirquit for the electrodes 8 there is inserted anautomatical switch device 19 which is connected so as to control theoperation of the electromagnetic inlet valve 6 responsive to variationin the current between the electrodes 8. The switch device 19 is soadjusted that it causes the valve to open when the electrode current isas small as corresponding to a certain low water level in the container(level a) and to close when the water reaches a certain higher level(level b). It will be understood that the resulting electricalresistance between the electrodes is highly dependant of the height ofthe water level, so it is easy to automatically register the currentvariation in the unit 19. The detailed design of this unit is a matterof ordinary skill and should need no further description in the presentconnection.

It will be readily understood that with the arrangement shown the switchdevice 19 will serve to automatically cause a refilling of water intothe container every time the water sinks to the level a, so thegenerator may work constantly in a self controlled manner.

For the operation it is a condition that the water is electricallyconducting, i.e., that the water contains minerals or the like. However,this is always the case with water in ordinary water supply systems, andfor the same reason the steam production will give rise to considerableprecipitation adjacent the container bottom. In order to obtain anautomatic rising out of the precipitations the electromagnetic valve isoperatively connected with a time switch device 20 which serves to openthe valve 16 for a short period with suitable, preferably adjustabletime intervals. It is an important feature that the draining pipe system12, l4, 16 is of large diameter whereby a strong outlet flow is producedso that also larger precipitated material pieces may be rinsed out.

As shown also in FIG. 2 the inlet pipe 4 is connected to the containerin an almost tangential position thereto. It is hereby obtained that theprecipitations will be agitated every time water is let into thecontainer, whereby the formation of solid deposits on the bottom is tosome degree counteracted, since in nonnal operation it is preferred tolet the valve 6 open relatively often, e.g., at intervals of 10 secondsto 2 minutes, the opening time being, e.g., few seconds only.

As mentioned, it is a special and important feature of the inventionthat-as illustrated by an electrical connection 22 between the timer 20and the inlet valve 6- that the inlet valve 6 is opened concurrentlywith the opening of the outlet valve 16, i.e. during the rinsing out ofthe container. Hereby it is ensured that practically all looseprecipitations are rinsed out. The rinsing outlet valve 16 may beopened, e.g., two to four times per hour for asteam productioncorresponding to a consumption of about 5 liters of water per hour.However, the optimal rinsing intervals will be highly dependam of themineral contents'of the water. The opening time of the valve 16 may beadjusted to, e.g., 5-15 seconds.

When the water has been rinsed out and the valve 16 is closed the valve6 will remain open until the new water reaches the level b, whereafterthe described operation cycles will be repeated.

The invention is not limited to the embodiment shown, since, e.g., theclosing of the valve 6 after each period of water introduction may beeffected by means of a timer rather than by registration of increasedcurrent. The operation intervals of the outlet valve 16 may becontrolled by means of a counter registering a predetermined number ofoperations of the inlet valve 6 and serving to operate the valve 16every time this number, e.g., 50 refilling operations, has been reached.

In order to obtain an improved agitation effect of the inlet water theinlet pipe 4 from the valve 6 may be substituted by more pipes connectedto different inlet openings of the container at desired inlet anglesrelatively thereto.

What is claimed is:

l. A steam generator comprising:

a water container having a steam opening outlet positioned in thevicinity of the top of said container, a water outlet opening locatedadjacent the bottom of said container and a water inlet opening;

heating means for heating the water in said containe to produce steam;

a water source for providing water to said container;

an inlet pipe connected between said water source and said water inletopening, said inlet pipe and said water inlet opening being located soas to direct inlet water generally toward the bottom of,

said container in a manner such that substantially all of the wateradjacent said bottom and undissolved impurities contained therein areagitated;

an inlet valve disposed in said inlet pipe adapted to adjust the amountof inlet water supplied to said container in accordance with the volumeof water leaving said container as steam;

a drain pipe connected to said water outlet opening;

an automatically operable outlet valve inserted in said drain pipeadapted to adjust the amount of water leaving said container throughsaid drain coliii 'c il rii ans operatively associated with said inletand outlet valves adapted to intermittently actuate said inlet valvewith relatively short time intervals and said outlet valve withrelatively long time intervals.

2. A steam generator according to claim 1, in which said inlet openingis located spaced from said outlet opening.

3. A steam generator as claimed in claim 1, in which the cross sectionalarea of the outlet opening and the drain pipe is at least twice thecross sectional area of the water inlet pipe.

4. A steam generator according to claim 1, in which said inlet valve isautomatically operable to open and close said water inlet, whereas saidcontrol means for said outlet valve are operatively connectedadditionally with said inlet valve so as to cause said inlet valve to beopen during at least a period of the time intervals in which the outletvalve is open.

5. A steam generator according to claim 1, in which said inlet valve isautomatically operable to open and close said water inlet, whereas saidcontrol means for said outlet valve are operatively connectedadditionally with said inlet valve so as to cause said inlet valve toopen immediately prior to opening of said outlet valve.

6. A steam generator according to claim 1, in which the water containeris an upright cylinder having a circular bottom and the water inlet pipeis connected to the container adjacent the bottom thereof and with anorientation so as to let water into the container substantiallytangentially to the inner circumference of the container.

7. A steam generator according to claim 1 wherein said heating meanscomprise electrodes projecting into the water in said container whichare adapted to heat said water by means of a direct current passingtherethrough.

1. A steam generator comprising: a water container having a steamopening outlet positioned in the vicinity of the top of said container,a water outlet opening located adjacent the bottom of said container anda water inlet opening; heating means for heating the water in saidcontainer to produce steam; a water source for providing water to saidcontainer; an inlet pipe connected between said water source and saidwater inlet opening, said inlet pipe and said water inlet opening beinglocated so as to direct inlet water generally toward the bottom of saidcontainer in a manner such that substantially all of the water adjacentsaid bottom and undissolved impurities contained therein are agitated;an inlet valve disposed in said inlet pipe adapted to adjust the amountof inlet water supplied to said container in accordance with the volumeof water leaving said container as steam; a drain pipe connected to saidwater outlet opening; an automatically operable outlet valve inserted insaid drain pipe adapted to adjust the amount of water leaving saidcontainer through said drain pipe; and control means operativelyassociated with said inlet and outlet valves adapted to intermittentlyactuate said inlet valve with relatively short time intervals and saidoutlet valve with relatively long time intervals.
 2. A steam generatoraccording to claim 1, in which said inlet opening is located spaced fromsaid outlet opening.
 3. A steam generator as claimed in claim 1, inwhich the cross sectional area of the outlet opening and the drain pipeis at least twice the cross sectional area of the water inlet pipe.
 4. Asteam generator according to claim 1, in which said inlet valve isautomatically operable to open and close said watEr inlet, whereas saidcontrol means for said outlet valve are operatively connectedadditionally with said inlet valve so as to cause said inlet valve to beopen during at least a period of the time intervals in which the outletvalve is open.
 5. A steam generator according to claim 1, in which saidinlet valve is automatically operable to open and close said waterinlet, whereas said control means for said outlet valve are operativelyconnected additionally with said inlet valve so as to cause said inletvalve to open immediately prior to opening of said outlet valve.
 6. Asteam generator according to claim 1, in which the water container is anupright cylinder having a circular bottom and the water inlet pipe isconnected to the container adjacent the bottom thereof and with anorientation so as to let water into the container substantiallytangentially to the inner circumference of the container.
 7. A steamgenerator according to claim 1 wherein said heating means compriseelectrodes projecting into the water in said container which are adaptedto heat said water by means of a direct current passing therethrough.